A neuroma is generally used to describe a
chronic pinched nerve that develops a mass of scar tissue around it as a result
of that chronic irritation.

Is a Morton's neuroma the same thing as a
neuroma?

Not exactly.

The term "Morton's
neuroma" is only properly used to describe the condition when the
affected nerve is the one that supplies the adjacent sides of
the third and fourth toes. (See diagram to the right.)

The word "neuroma" could
be used to describe a chronically pinched or irritated condition of
any nerve--say, the nerve providing nervous sensation to the second
and third toes, for example.

That's how the words
"neuroma" and "Morton's Neuroma" are used today,
but in truth, neither phrase is really a proper term.

How so?

First, it's not really a neuroma.
Adding the Greek suffix "-oma" to a word literally means
"tumour". That's why we attach it to words referring to
cancerous conditions like lymphomas and benign tumours like fibromas.

But a neuroma is not really a tumour at all.
It's actually a growth of scar tissue around a nerve, due to chronic irritation.
Instead of our using the word "neuroma", the more proper name for the
condition would be "perineural fibrosis", which literally translates
to "scar tissue around the nerve".

The second reason the condition is misnamed is
that the Morton's neuroma wasn't really first described by Morton.
The first to accurately describe the condition was a chiropodist to the Queen of
England, Louis Durlacher. In 1845 he accurately discerned that the
condition was a nerve problem.

Thirty-one years later, in 1876, Thomas G.
Morton, a physician in Philadelphia, described a type of discomfort in the
region as being an inflammation of the fourth
toe joint (the fourth metatarsophalangeal joint). Today we'd
describe this condition joint problem as "capsulitis". (You can
read more about capsulitis in the section below entitled "What
Other Conditions Mimic a Neuroma?".)

In any event, what we know today as a Morton's
Neuroma should probably be called Durlacher's Perineural Fibrosis. It goes to show you that getting it right and
getting it first is sometimes worse than getting it wrong and getting it decades
late.

What nerves are
affected?

The most common
location for a neuroma to develop is the classic "Morton's
Neuroma" location--involving the nerve that supplies sensation to
the third and fourth toes. This is the location in over 80% of
cases, with the nerve between the second and third toes involved in
15% of cases.

This nerve lies deep in
the foot, and represents joined branches from the medial and lateral
plantar nerves.

For more information
about nerves in the feet, visit our page on neurology.

Why does the condition develop?

Several theories have been put
forth as to how the nerve is exactly irritated. The irritation to
the nerve may come from chronic friction caused by the adjacent metatarsal
bones, the adjacent toe bones or Deep
Transverse Metatarsal Ligament between the
metatarsals under which the afflicted nerve passes en route to the toes.

But because the Morton's Neuroma
involves the joined branches of two nerves coming together, it is likely that
the enlargement where those nerve join together predisposes that nerve to
irritation.

Who gets neuromas?

Anyone can get a neuroma, but it is more
commonly seen with women and in middle age. The most common precipitating
factors are having a foot that flattens too much (a pronated
foot), having
contracted toes
or some other similar pathology, and making poor shoe choices. (Tight toe
box shoes and high heels are the worst choices.)

What does it feel like?

Symptoms vary. Sometimes the
patient simply experiences numbness, or diminished sensation. It
may also feel simply like sensation inappropriate to the degree of stimulus, for
example, pain with light touch of the skin, or feeling as though there's
something inside the shoe when there is nothing present.

But the most common
feeling is one of a sharp, stabbing pain in the ball of the foot or
toes.....................

...............or like a
severe sudden jolt of electricity shoot up the leg or down to the end
of the toes--particularly if the foot is squeezed.

What other conditions mimic a neuroma?

There are quite a few potential differential diagnoses
(possible alternative diagnoses):

Capsulitis
Joint capsule is the covering that extends around a joint, so capsulitis is
an inflammation of that joint covering. There are two major
joints immediately adjacent to the location where neuromas develop--one on
each side of the nerve. Capsulitis is more likely in conditions
where there is an abnormality associated with those joints, such as a hammertoe,
or if there is abnormal or excessive flattening of the feet, or pronation.
For more information on capsulitis,
visit its entry under our metatarsalgia
page.

Synovitis (inflammation
of the joint fluid known as synovium) is closely-related to capsulitis.
In fact, the synovial fluid is actually manufactured by the capsule.
Some believe that if you have capsulitis, you also have synovitis.

Joint subluxation
In cases where the joint is misaligned enough, the base of the toe bone may
actually tear through the capsule, causing a dislocation of the joint.
Once considered rare, this diagnosis seems to be much more commonly picked
up than in years past.

Degenerative arthritis Arthritis
may develop in the joints in the area, mimicking the symptoms of a neuroma.
This sort of arthritis comes from repetitive trauma to the joint.

Other rheumatolgical conditions
(other types of arthritis)
may affect the joints adjacent to the classic location of a neuroma.
This is particularly true of Rheumatoid Arthritis and Psoriatic Arthritis.

Metatarsalgia
The word "metatarsalgia" literally means pain in the bones in the ball of the foot (the
metatarsals), and so, it is really a vague term. It would probably be best described as a bruise to the metatarsal
bones adjacent to the nerve.

Stress fractures
One step beyond metatarsalgia, stress
fractures are small cracks in the
metatarsals or toe bones that develop over time as a result of
excessive strain or stress.

Avascular necrosis Avascular necrosis
is a degenerative condition where the constant stress to the metatarsal
bones gets severe enough that a portion of the bone actually begins to die.

Tendinitis
There are a lot more tendons in the area of the classic neuroma location
than you might think, any one of which may develop tendinitis.
Tendons to the Flexor Digitorum Longus, Flexor Digitorum Brevis, Extensor
Digitorum Longus, Extensor Digitorum Brevis, the 3rd Dorsal Interosseus, the
2nd Plantar Interosseus and the 3rd Lumbrical muscles all attach in the area
immediately adjacent to the classic neuroma location.

If the sensation varies so much, and if other
conditions cause symptoms similar to those of a neuroma, how do I know what I
have?

Diagnosis is not easy sometimes. The classic test
for a neuroma is the "Mulder's Sign".
The foot is grasped and squeezed from the sides with one hand, with the other
hand pushing the nerve up in between the third and fourth metatarsal bones.
When this test is positive, the nerve gets squeezed and creates a clicking
sound, and often severe pain in the foot.

While this test often works well for well-established
neuromas, it doesn't work in every case. As the sensation caused from a
neuroma may vary a great deal, and as there are several structures in the
immediate area that can create similar sensations as a neuroma, definitive
diagnosis of this condition can be elusive. For this reason, neuromas are
frequently diagnosed as something else, and it is particularly common that other
conditions of the foot are mis-labeled as being a neuroma. For this
reason, it is important to have a foot specialist examine you for this
condition.

How do you treat a neuroma?

Many treatments have been developed for short-term
relief of the symptoms of a neuroma. Rest, ice, elevation,
anti-inflammatory medications, steroid injections, physiotherapy, taping,
padding, immobilization are all common early treatments.

Long-term, making different choices in shoes may be
required. And changes in the types of activities chosen may be helpful.
(For example, using a stair-climbing machine at the gym may not be advised.)
Orthoses are very helpful with controlling any abnormal mechanical motions and
with diminishing pressure to the affected nerve. There are
special additions that may be made when a neuroma is diagnosed.

When more conservative means fail, more invasive
techniques may be required. One possibility is to cauterize the nerve with
a specialized alcohol injection. Often effective, this treatment may
require a series of several injections to resolve a neuroma.

When nothing else is helpful, surgical intervention to
remove pressure from the nerve, or to remove the nerve, may be necessary.

What's the surgery like?

The surgery consists of making a small incision on the
foot, either from the top or bottom, then carefully dissecting the afflicted
nerve out from the surrounding tissue and removing the diseased portion.
Sometimes the ligament that lies on top of the nerve is cut to allow the
remaining nerve more room. The procedure may be done under local
anaesthesia, and the patient is typically allowed a limited amount of walking
immediately after the procedure.

Left: A typical
two-pronged pitchfork appearance of an excised neuroma. The two
branches on the left are the branches that would supply innervation to
the third and fourth toes. The long branch on the right is
the branch coming into the toes from the foot.

Some authors report only an 80% success rate
with this surgery (meaning about 20% have little or no improvement after the
surgery), but we find the success rate to be higher when patients are properly
chosen. (We believe that other similar conditions are frequently
misdiagnosed as being a neuroma, that appropriate conservative treatments are
under-utilized, and inappropriate surgical intervention is too quickly
suggested.)

How do you prevent a neuroma?

Wear good, supportive shoes. Avoid
pointed toe boxes and high heels. If you have a foot that flattens
excessively in stance, it is a good idea to get a proper early.
And if your foot has some other pathology that is causing the formation of this
condition, (like hammertoes
or abnormal or enlarged bones near the neuroma), this may need to be addressed
to avoid the development of a neuroma.